We have this spider living in our greenhouse several months. We have living plants from Kenya and South Africa. Does anyone know which kind of spider it is, and if it is potentially invasive?
I agree with Jens, most likely a Loxosceles species. we've worked with a few over the years. can you see if they only have 6 eyes on the original photo? this is a key feature of the family Sicariidae
That's supposedly Loxosceles reclusa and that photo was taken from the internet: http://www.museum.state.il.us/ismdepts/zoology/spiders/gallery.html?RollID=roll03&FrameID=loxosceles_reclusa
You might want to try to photograph the actual spider, but it might well be Loxosceles rufescens, which is often found inside houses in southern Iberia. Be careful with it, although the venom is not as bad as that of L. reclusa.
Here in Brazil is known as brown spider (Loxosceles), is poisonous and causes tissue loss after the bite. I have information that does not complete its cycle in Austria for not resitir the harsh winter. Not sure how its biology in other parts of europe.